Method of forming sensitive record track on cinematographic film



April 29, 1952 E. E. GRIFFITH ET AL METHOD OF FORMING SENSITIVE RECCRD TRACK 0N 'CINEMATOGRAPHIC FILM Filed NOV. 20, 1948 Patented Apr. 29, 1952 METHOD OF FORMING SENSITIVE RECORD TRACK ON CINEMATOGRAPHIC FILM Everette E. Griffith and Lauriston E. Clark, Los Angeles, Calif., assignors to Technicolor. Motion Picture Corporation, Hollywood, Calif., a corporation of Maine Application November 20, 1948, Serial No. 61,282

6 Claims.

In the production of motion pictures in color much difliculty has been experienced in produc ing satisfactory sound tracks. Colored sound tracks are unsatisfactory because practically-all dyes suitable for printing pictures have high transmission in the infrared range where photocells have a substantial percentage of their sensitivity; and no way has been found to produce on color film a black-and-white sound track which is both satisfactory and commercially feasible.

Objects of the present invention are to form on cinematographic film or the like a sensitive track, for sound records or other records, without adversely affecting the remaining width of the film, and more specifically to produce motion pictures in color with a sound track by a process which afiords high quality sound reproduction and which is economical and otherwise commercially feasible.

In one aspect the present invention involves a method of forming a sensitive record track on cinematographic film which comprises separately applying to the film two liquids which together impart to the film water-insoluble sensitizing material, one liquid adversely affecting a "recorddefining characteristic of the film and being confined to a narrow longitudinal zone of the film. Preferably one liquid contains water-soluble sensitizing material such as metal salt and the other comprises a fixation agent or precipitant to convert the salt into a water-insoluble light-sensitive compound. While the order may be reversed, the water soluble material is preferably applied first and the insolubilizing material subsequently.

In another aspect the invention involves printing picture adjacent the sound track, preferably by imbibition. In some cases, as with silver and thallium salts, it is advisable if not necessary to follow the imbibition printing with a precipitant treatment to prevent migration or bleeding dur ing the subsequent steps.

After having formed the light-sensitive band or track a record is formed in the track by exposure to light or by application of a chemical to which the track is sensitive. When exposing to light the film may be exposed through a matrix, negative or the like, thereby to form exposed and unexposed areas which define the sound track or other optically effective track. Thereafter one of these areas is developed and the other area may or may not be fixed depending upon the particular light-sensitive compound used.

- In a still more specific aspect the preferred method contemplates striping the sound-track zone with a light-sensitizing solution such as aqueous silver nitrate, in which case theentire film is bathed with a silver halide precipitant such as sodium chloride, after which the pictures are printed in color and the sound track is printed in silver, the printing preferably being carried out mechanically as by imbibition. In striping on the sensitizing solution, preferably an excess is applied and then, after a predetermined period of time, the excess is removed by suction.

Where, as is preferred, the light-sensitive compound is applied by a striping device, the developer is likewise applied to the sound track zone by a striping device after which the excess developer is removed by suction and the sound track zone is fixed by bathing the entire film in a fixing bath. 1

By using a silver halide precipitant which does not injure the picture zone, the precipitant need not be striped on, and the same is true of the fixing solution. Thus a satisfactory sound track can be produced economically without injury to the picture zone.

For the purpose of illustration a typical embodiment of the invention is illustrated in the accompanying drawings in which: Fig. 1 is a diagrammatic view of a system for practicing the process;

Fig; 2 is a sectional view of a suitable striping device Fig. 3 is a plan view of the striping device, showing its relationship to the film;

Fig. 4 is a similar view of a suction device; and

Fig. 5 is a side elevation of the suction device.

The particular embodiment of the invention chosen for the purpose of illustration comprises a pin-belt I trained over two drums or wheels 2 and 3, the pin-belt having rows of teeth along its margins for engagement in the sprocket holes of motion picture film as disclosed in the patent to Whitney 1,707,699. Two films F and. M are fed to the belt in a water tank 4 having narrow slits to permit the passage of the pin-belt therethrough. As disclosed in the patent to Whitney the slits may be so constructed that very little water leaks out and the leakage can be offset by continuously adding water to the tank. Inside the tank are two pairs of seating rolls 6 and l for separately seating the films on the belt. The film F may comprise a so-called blank such as used in imbibition printing, the blank having a coating of gelatin hardened to the necessary degree to receive imbibition prints from the matrix M. Before the matrix M is fedto the pin-belt through a tank 12 containing water to moisten the film, thence past a bubbler l3 which applies the silver sensitizing solution, thence past a suction device 14 thence through a tank ('5 for bathing the entire film with silver halide pre- 1 cipitant thence through a wash tank [1 and thence through a dry box 18 which partially or wholly dries the film. If the film is wholly dried it is caused to loop back and forth in the water tank 4 as indicated at 19 in order to remoisten it before contacting the matrix M. By wholly drying the film and then remoistening it, it is easier to give the film exactly the right amount of moisture to receive the imbibition print from the matrix M. By regulating the speed of the film F in relation to the distance between the bubbler l3 and the suction device hi the sensitizing solution is left on the sound-track zone of the film long enough to seconds) for the requisite amount to soak into the gelatin coating of the film.

The bubbler 13 comprises a nozzle 2! and a surrounding casing 22 with a space 23 there between to receive overflow from the bubbler and an outlet 24 for returning the overflow solution to the reservoir from which it is supplied to the bubbler. As shown in Fig. 1 the nozzle 2| is preferably inclined in the direction of film travel, that is to the right. Opposite sides of the nozzle tip, in the direction of film travel, are beveled (Fig. 2). sensitizing solution is applied to the nozzle through a tube connection at its lower end similar to the outlet 24 for the overflow. The liquid is supplied at low pressure so that the fountain of liquid issuing from the nozzle rises only slightly above the tip of the nozzle. The fountain is so adjusted that its summit wets the film continuously across the sound track zone but without wetting the picture areas 21. By applying the solution in this way the width of the strip can be regulated precisely by varying the rate of flow and a rounded ridge of the solution is left adhering to the film gradually to soak in while the film travels from the bubbler 13 to the suction device hi. As shown in Figs. 4 and 5 the suction device has a slot extending transversely of the sound-track zone, the length of the slot being substantially equal to or slightly greater than the width of the sound-track zone. By placing the tip of the nozzle close to the film as shown in Fig. 5 all of the solution which has not soaked in is removed.

After the two films F and M have passed through the printer I I, photographically to print on the film F the sound track carried by the film M, the two films travel on the belt I in intimate contact with each other throughout a path long enough to permit the dye absorbed by matrix M to be imbibed by the gelatin coating on the film F. Then the filmsare fed from the belt at rollers 28 and 29. The matrix M may be fed through a dry box 31 and thence to a take-up reel 32, but before drying the film F the sound track is developed and fixed. According to this invention this is preferably accomplished as follows. The v film is first fed past a bubbler 33 similar to the bubbler l3, thence past a suction device 34 like the device l4, thence through a tank 36 containing the fixing bath, thence through a Wash tank 31 and thence through a drier 38 to the take-up reel 39. The bubbler 33 applies to the soundtrack zone a ridge of developer which is removed by the suction device 34. By suitably spacing the devices 33 and 34 in relation to the speed of the film the sound track may be developed to the proper degree while the film is traveling from 33 to 34.

While various formulae may be employed for the sensitizing solution, the silver halide precipitant, the developer and the fixing soltuion the following are recommended:

Silver sensitizing solution Gms. per liter Silver nitrate 50 Silver halide precipitant Gms. per liter Sodium chloride Firing solution Gms. per liter Sodium thiosulfate 1 2-0 1 pl]; adjusted to 4-5 with acetic acid.

It should be understood that the present disclosure is for the purpose of illustration only and that this invention includes all modifications and equivalents which fall within the scope of the appended claims. For example in making two-color pictures two matrices would be pressed against the film F successively and in making three-color pictures three matrices would be pressed against the film F successively. Successive printings can be effected either on separate pin-belt machines or on the same machine. If efiected on the same machine the film F may be fed through the machine two or three times with different matrices or the machine may be so arranged that the difi'erent matrices are pressed against the blank successively in a single passage of the film F through the machine, as disclosed for example in Patent 2,415,442. Instead of forming a sound record in the sensitized zone any other kind of a record may be formed, as for example a control record such as disclosed in copending application Serial No. 619,315, filed September 29, 1945, now Patent No. 2,495,821.

We claim:

1. In the art of printing dye-absorbent motion picture film, the method which comprises striping one longitudinal zone of the film with a water-soluble silver salt, subsequently bathing the entire film with a water solution of a water soluble halide to form a light sensitive waterinsoluble silver halide in said zone, and subsequently superposing the film and a dye-soaked matrix to print pictures on the film by imbibition and printing said longitudinal zone of the blank by exposure through a record track, whereby the record track may be printed in silver with the high definition afforded by exposure of a silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

2. In the art of printing on dye-absorbent motion picture film with a matrix carrying a record track and a relief picture record soaked with an aqueous dye, the method which comprises striping one longitudinal zone of the film with a water-soluble silver salt, subsequently bathing the entire film with a water solution of a water soluble halide salt to form a light sensi tive water-insoluble silver halid in said zone, and subsequently superposing the matrix and film to transfer the aqueous dye by imbibition to another longitudinal zone of the film and printing the first said longitudinal zone of the film by exposure through said record track, whereby the record track may be printed in silver with the high definition afiorded by exposure of silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

3. In the art of printing on dye-absorbent motion picture film, the method which comprises striping one longitudinal zone of the film with a solution of silver nitrate, subsequently bathing the entire film with an aqueous solution of sodium chloride to form light sensitive water-insoluble silver chloride in said zone, and subsequently superposing the film and a dye-soaked matrix to print pictures on the film'by imbibition and printing the first said longitudinal zone of the blank by exposure through a sound-record track, whereby the record track may be printed in silver with the high definition afiorded by exposure of a silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

4. In the art of printing on dye-absorbent motion picture film with a matrix carrying a record track and a relief picture record soaked with an aqueous dye, the method which comprises striping one longitudinal zone of the blank film with a solution of silver nitrate, subsequently bathing the entire film with a aqueous solution of sodium chloride to form a light sensitive water-insoluble silver chloride in said zone, subsequently superposing the matrix and film to transfer the aqueous dye by imbibition to another longitudinal zone of the film and printing the first said longitudinal zone of the film by exposure through said record track, whereby the record track may be printed in silver with the high definition afforded by exposure of silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

5. In the art of printing dye-absorbent motion picture film, the method which comprises striping one longitudinal zone of the film with a water soluble silver salt, bathing the entire film with a water solution of a Water soluble halide to form a light sensitive water-insoluble silver halide in said zone, subsequently superposing the film and a dye-soaked matrix to print pictures on the film by imbibition and printing said longitudinal zone of the blank by exposur through a record track, and subsequently striping said zone of the film with developer, whereby the record track may be printed in silver with the high definition afforded by exposure of a silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

6. In the art of printing dye-absorbent motion picture film, the method which comprises striping one longitudinal zone of the film with a water-soluble silver salt, bathing the entire film with a water solution of a water soluble halide to form a light sensitive water-insoluble silver halide in said zone, subsequently superposing the film and a dye-soaked matrix to print pictures on the film by imbibition and printing said longitudinal zone or" the blank by exposure through a record track, subsequently striping said zone of the film with developer and subsequently bathing the entire film with fixing solution, whereby the record track may be printed in silver with the high definition afiorded by exposure of a silver salt and the pictures may be printed in colored dye without interaction of the dye and the silver salt.

EVERETTE E. GRIFFITH. LAURISTON E. CLARK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS D. Van Nostrand Co., New York, 1888, pp. 29-33. 

